Radeon 4870 broken in HL2 engine?

This card was working fine, all of a sudden it can't even play any game on the HL2 engine well. Before of course this card was performing well, I can't remember changing anything and all of a sudden I can't even handle 4 people on screen in TF2 or handle more than a few zombies in Left 4 Dead, it drops my framerate down to 20-30 fps.

My system:
E6600 @ 3.1 ghz, Radeon 4870, 4 gigs Pc1000 DDR2, creative x-fi, 650 watts psu (not generic)

I loaded up GPU-Z on my second monitor and I noticed my GPU Load is 0% on TF2 while its 100% on STALKER and 50-80% on Fallout 3.

I've already tried reinstalling drivers, reinstalled directx, disabled onboard sound drivers in system, made sure pcie frequency is at 100mhz, made sure ram timings and voltages were correct, made sure cpu is NOT underclocked, turn off cpu throttling in bios, made sure pci express is running at 16x, I even tried overclocking my radeon, didn't make much of a difference.

Should I just format?

Try to alt tab ingame. I'm having strange fps with my hd4870x2 as well until I alt tab out and back in.

I tried it but there was no change.

I came upon this post http://www.hardforum.com/showthread.php?t=1340208
this guy had the same problem as me, except he had a 4850 and it looks like he never found a solution.
Same with this guy http://forums.overclockers.co.uk/showthread.php?p=12583370

It looks like I will have to RMA. What an odd way for a video card to die.

Update: seems to be an issue with Vista (64 bit?)

Or it could be my cpu/mobo. I ran Sandra Lite 2009 and my cpu benchmark came BELOW the e6600. I am running an overclocked e6600.

But I also noticed that for some reason my hard disk was continuously thrashing so I ran process monitor and sony ericson software kept on accessing the disk. That didn't really fix it. Anyway going to format and hope it's not a hardware issue.

Try disabling superfetch for a bit, some have said that it's slowed game performance to a crawl because of the constant disk access.